mongodb/kingfisher v1.60.0 on GitHub

[v1.60.0]

Removed the --bitbucket-username, --bitbucket-token, and --bitbucket-oauth-token flags in favour of KF_BITBUCKET_* environment variables when authenticating to Bitbucket.
Added provider-specific kingfisher scan subcommands (for example kingfisher scan github …) that translate into the legacy flags under the hood. The new layout keeps backwards compatibility while removing the wall of provider options from kingfisher scan --help.
Updated the README so every provider example (GitHub, GitLab, Bitbucket, Azure Repos, Gitea, Hugging Face, Slack, Jira, Confluence, S3, GCS, Docker) uses the new subcommand style.
Legacy provider flags (for example --github-user, --gitlab-group, --bitbucket-workspace, --s3-bucket) still work but now emit a deprecation warning to encourage migration to the new kingfisher scan <provider> flow.
Kept the direct kingfisher scan /path/to/dir flow for local filesystem / local git repo scans while adding a --list-only switch to each provider subcommand so repository enumeration no longer requires the standalone github repos, gitlab repos, etc. commands.
Removed the legacy top-level provider commands (kingfisher github, kingfisher gitlab, kingfisher gitea, kingfisher bitbucket, kingfisher azure, kingfisher huggingface) now that enumeration lives under kingfisher scan <provider> --list-only.